What are renewable energy sources?
Renewable energy sources are becoming more and more prevalent around the world, but it is still not the dominant energy resource. -By Chris Bradshaw from Renewables Guide
Since the industrial revolution began in the 18th and 19th centuries, we’ve been burning fossil fuels such as oil, coal and natural gas to fuel our homes, businesses and transport.
However, while fossil fuels have enabled huge economic growth and technological evolution, we now know that burning them has also damaged our planet through the vast amounts of carbon we’ve put into the atmosphere. Carbon emissions are causing our planet’s climate to change so drastically that it could eventually lead to widespread drought, flooding and massive population displacement caused by rising sea levels.
If that weren’t enough reason to find alternative sources of energy, fossil fuels are non-renewable, i.e. they take millions of years to form. This means that once they’re gone, they’re gone, and they are running out. This is why more and more of us are turning to renewable energy sources.
In one form or another, solar power has been around for thousands of years. As a renewable source of free, green energy, technology has found a way of harnessing the sun’s energy via solar panels.
There are 2 types of solar panels: solar photovoltaic (PV) and solar thermal.
Solar PV systems capture the energy from the sun’s light and convert it into usable electricity which we can use to power everyday appliances, electric heating or even to run electric cars.
Solar thermal panels use the sun’s energy to heat water which can then be used in taps, showers and wet central heating systems. A popular choice in a growing renewable energy market, solar energy is free and means owners need to buy less energy from a supplier.
Air or Wind
An abundant source of renewable energy, the very air around us can be used to generate both heat and electricity.
Air source heat pumps are becoming more and more popular with homeowners and businesses looking to heat buildings with a renewable energy source. An air source heat pump operates like a refrigerator in reverse. A unit which is visually a lot like an air conditioning unit sits outside your home and draws in air via a rotating fan. A refrigerant chemical then absorbs the latent heat from the air so the heat can be used in the home. In an air-to-air heat pump this heat is used to heat the space in your home while in an air-to-water heat pump the heat produces hot water for domestic use and a wet central heating system.
Air source heat pumps can still work effectively even in temperatures as low as -20°C in some cases and, as well as reducing your home’s carbon footprint, can significantly reduce heating bills when replacing a traditional oil or LPG boiler.
Wind power is used as a means of generating electricity by wind turbines which are capable of harnessing the power derived from the wind, converting kinetic energy into mechanical energy. A source of clean, green renewable energy, favourable climate conditions in Europe means wind energy is a highly viable method for electricity generation. And none more so than in the UK, with 40% of all wind energy in Europe blowing over the country.
Biomass energy is a renewable energy source because it is produced from organic materials such as plants and manure. The most common forms used to generate biomass energy are wood, crops and manure. However, the energy that is produced in this way can be traced back to the energy provided by the sun.
For example, plants and trees absorb the sun’s energy through a process called photosynthesis so when we burn wood or crops we are actually harvesting the sun’s energy. In the case of manure being used as a fuel this is also energy from the sun, but it has been passed on through the organism that ate the plant, creating biomass energy.
Biomass boilers burn wood pellets, wood chips or logs, using the generated heat to produce hot water for wet central heating systems. In some cases they can also be fueled by biological material from plants and plant-based organisms.
Burning wood rather than gas or oil is much more sustainable as we can plant and grow new trees but we can’t replace the gas or oil we’re currently burning for fuel without waiting a few million years. This is not the only method of generating biomass energy; you can also create biomass energy by converting these substances into methane gases, ethanol and biodiesel fuels which can be translated more easily into our current methods of energy use.
Geothermal & Ground Source
Geothermal comes from the Greek word “Geo” which means earth, so geothermal energy is derived heat from the Earth. For example, steam energy or hot water that is generated by the Earth can be used to generate energy. It is considered to be a renewable source of energy as the water in the Earth is replenished by regular rainfall and the heat used is regularly produced by the planet.
Ground source heat pumps can be installed to harness the natural heat from underground via tubes of fluid buried outside the property. This fluid absorbs the heat from the ground so it can be used to heat your home and water. The tubes can either be installed straight down, deep underground or horizontally if you have enough outside space. Using renewable energy to produce heat for your home means you will need to buy less from a supplier and so should be able to reduce your heating bills as well as your carbon emissions.
Heat can also be extracted from natural sources of water. For properties situated near a lake, river or stream it’s possible to install a water source heat pump. Pipes are submerged in the water and a heat pump pushes a heat absorbing fluid through the network of piping; this fluid extracts natural heat from the surrounding water to be used in the heating system.
Hydro power or hydro energy is derived from the movement of water, rather than the natural heat of water. One form of hydro power is generated through the movement of water through turbines, such as water running through turbines in a dam. Hydro power is considered a renewable energy source as the water is continuously cycled back through the plant or into nature.
Biofuels are a form of renewable energy derived from burning plant or animal substances, otherwise called combustion. One of the challenges to biofuels has been that it is not easily transferred into a liquid form which is the primary method used to fuel most cars and homes.
Two of the most common strategies that are said to produce biofuels includes: growing crops to produce ethanol and growing plants that produce biofuel oils. While these methods are effective sources of renewable energy, they are challenging to produce and maintain on a large scale.
Should You Switch to a Renewable Energy Source?
It’s widely accepted that we need to make a change to cleaner and renewable energy sources if we want our planet to survive for as long as possible. The Paris Agreement in 2015 brought the world’s leaders and governments together to centralise the global response to the threat of climate change.
There have been several incentive schemes and grants on offer to encourage us to make the change to renewable energy sources such as the Renewable Heat Incentive (RHI) which pays owners of eligible renewable heating systems for the energy the technology generates for 7 years after installation. This scheme is intended to reimburse the homeowner for as much as 80% of the initial purchase price over the 7 years but the tariff paid varies from technology to technology. The government were also running a scheme called the Feed-in Tariff (FiT) which paid owners of solar PV systems for the electricity they generate and fed back to the National Grid, but this scheme is due to close to new applications in March 2019.
The most common types of renewable energy found in homes today are:
Solar PV panels for renewable electricity generation for both homes and cars
Solar thermal panels for a renewable wet central heating system
Air source heat pumps for heating and / or hot water production
Biomass boilers for wet central heating systems
Ground source heat pumps for wet central heating systems.